Subterranean irrigation device and method of using the same

ABSTRACT

A subterranean irrigation system comprises a conduit that is attached to a soaker sheet having upper and lower permeable membranes that define a hollow interior there between. The hollow interior facilitates fluid flow there through while minimizing fluid flow resistance. The sheet typically includes a heat welded side seam along three sides of the upper and lower membranes to prevent the flow of water there through, wherein the remaining edge of the sheet is secured to the conduit. The sheet further includes a plurality of holes cut into the upper and lower membranes, wherein the hole pattern extends over the entire sheet. The holes allow the roots of grass or ground cover to grow through the soaker mat and simultaneously define channels of water flow around the holes between the upper and lower membranes.

TECHNICAL FIELD

[0001] The present invention relates to a subterranean irrigation devicefor lawns or the like, and more particularly, to a permeable membranesoaker sheet that is placed beneath sod or the like to water the sodfrom below.

BACKGROUND OF THE INVENTION

[0002] Large expanses of grass or ground cover, such as lawns, sportfields, playgrounds, and golf courses, typically are irrigated with anabove ground water system. In particular, flexible hoses with attachedsprinklers may be manually placed in a variety of locations on theexpanse of grass to irrigate the area. To maintain a pleasing aestheticappearance and to reduce tripping hazards, the hoses and sprinklers mustbe removed after each irrigation cycle. For some lawn uses, such as golfcourses, these manually placed systems are unacceptable.

[0003] As a result of the numerous disadvantages of these manuallyplaced sprinkler systems, permanently installed underground sprinklersystems have been developed. These underground sprinkler systems providewater through an underground pipe system, whereupon the water isdelivered to “pop-up” sprinkler heads that are raised above the surfaceof the ground during watering. While these automatic “pop-up” sprinklerheads have reduced the manual labor requirements of watering, thesesystems are often subject to breakage and leakage at the sprinkler head.Moreover, both the manual and the pop-up sprinkler systems provide waterin a fine mist above the grass or ground cover. It is estimated thatapproximately fifty percent of the water is lost to evaporation prior toreaching the ground.

[0004] Accordingly, fully subterranean irrigation systems have beendeveloped. These systems avoid the tripping hazards and waterevaporation problems of the above ground watering systems but are alsosubject to several disadvantages.

[0005] U.S. Pat. No. 6,161,776 to Byles discloses a multi-layered,porous mat turf irrigation apparatus and method wherein a continuous,three-layer system is disclosed. The mat comprises a central layer oflarge pore, lateral water distribution material that is sandwichedbetween two layers of small pore, vertical water distribution material.The disclosed system has several disadvantages. First, despite the largepore size of the central layer, the central layer of material providesresistance to the flow of water. Accordingly, the size of the mat isrestricted due to water pressure restrictions. Second, the continuoussheet of material, having the small pore material layers in contact withthe ground, provides a barrier to root growth there through.Accordingly, roots typically are prevented from growing downwardly pastthe top layer of the irrigation mat.

[0006] There is a need, therefore, for a subterranean irrigation systemthat has reduced resistance to liquid flow and which facilitates healthyroot growth of the grass or ground cover there through.

SUMMARY OF THE INVENTION

[0007] The present invention provides a permeable membrane soaker sheetthat is placed beneath sod to water the sod from below. The inventiontypically is used on lawns, sport fields, playgrounds, golf courses andthe like, where there are large expanses of grass without many trees orshrubs. A water conduit, which typically is manufactured of a solidmaterial such as PVC or copper piping, includes a fastener, such asthreads, at one end so that the conduit can be attached to a watersupply line, such as an underground watering system similar to anunderground sprinkler system. The conduit is attached to a sheet havingupper and lower permeable membranes that define a hollow interior therebetween. The hollow interior facilitates fluid flow there through whileminimizing resistance thereto. The sheet typically includes a heatwelded side seam along three sides of the upper and lower membranes toprevent the flow of water there through. The sheet further includes aplurality of holes cut into the upper and lower membranes, wherein thehole pattern extends over the entire sheet. The holes are defined by aheat welded seam around each individual hole. In one embodiment theholes have a size of approximately two inches by two inches. However,the holes may be of any size, shape or arrangement. The holes allow theroots of grass or ground cover to grow through the soaker mat andsimultaneously define channels of water flow around the holes betweenthe upper and lower membranes.

[0008] During installation of a grass lawn, the soaker sheet is placeddirectly on exposed dirt. The water conduit system is typically buriedslightly lower than the soaker sheet (and is connected to a watersystem) so that the conduit is not easily damaged. Grass sod is placeddirectly on the soaker sheet or on dirt placed directly on the soakersheet. The grass is watered by turning on the water supply to theconduit. In this manner, the roots of the grass are watered directly bywater that seeps through the permeable material, without evaporationloss. The disclosed invention is believed to result in a fifty percentreduction in water usage for large grass areas such as playing fieldsand golf courses. The system may also be used to evenly and safelydistribute fertilizers, weed killers, insecticides, and other chemicalsin liquid form to a large grassy area.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a partial isometric view of the subterranean irrigationdevice;

[0010]FIG. 2A is a side cross sectional view taken along line 2A-2A ofFIG. 1;

[0011]FIG. 2B is a side cross sectional view taken along line 2B-2B ofFIG. 1;

[0012]FIG. 3 is a top view of the soaker sheet system sized to fit aspecific shaped lawn area;

[0013]FIG. 4 shows a cross sectional, isometric view of anotherembodiment of the soaker sheet and conduit of the present invention.

[0014]FIG. 5 shows a top view of a subterranean irrigation system 10including several patches therein and wherein the system has beentrimmed to fit a particular sized turf area.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015]FIG. 1 is an isometric view of irrigation device 10 including awater conduit 12, which may be manufactured of a solid material such asPVC, copper or other rigid piping. Conduit 12 may also comprise flexiblepiping, such as piping made of rubber, flexible plastic or the like. Theconduit includes a fastener 14, such as threads, at one end so that theconduit can be attached to a water supply, such as an underground watersource as known in the prior art. Fastener 14 may comprise threads, asshown, a slip fitting, a “grabber” style fitting including an O-ring, orany other type of fastener. Conduit 12 is attached to a sheet 16manufactured of two fluid permeable membranes that define a space therebetween. Sheet 16 includes a heat welded side seam 18 that secures thetwo membranes together and prevents the flow of fluid there through.Side seam 18 typically extends around three sides of sheet 16. Sheet 16further includes a plurality of holes 20 cut into the fabric, whereinthe hole pattern extends over the entire sheet (only a small number ofholes are shown for ease of illustration). The holes typically extendthrough each of the permeable membranes wherein the two membranes aresecured together by heat welding, or other such connection means, aroundeach individual hole or aperture. Each of holes 20 typically has a sizeof approximately two inches by two inches. However, the holes may be ofany size, shape or arrangement. The holes allow the roots of grass orground cover to grow through the mat thereby providing for vigorous rootgrowth and stability of the grass or ground cover. This may beespecially important on sloped grassy areas. The edges of the holes aresealed so as to form channels of water flow 22 between and around holes20. The material that forms channels 22, i.e., the material of the topand bottom layers of the sheet, is manufactured of permeable material sothat a large “soaker sheet” is formed having a waffle type or grid typehole pattern therein. Due to the presence of holes 20 in the sheet, thesheet comprises an alternating pattern of semi-permeable material andholes. This pattern facilitates uniform watering of the grassy areaabove and below the soaker sheet while allowing space for root growthand stability of the turf.

[0016] During installation of a grass lawn, the soaker sheet is placeddirectly on exposed dirt. The water conduit system typically is buriedslightly lower than the soaker sheet (and is connected to a watersystem) so that the conduit is not easily damaged. Grass sod, or otherlike ground cover, is placed directly on the soaker sheet. Dirt may alsobe placed on the soaker sheet wherein sod, seeds or small rooted plantsare planted in or placed on the dirt. The grass is watered by turning onthe water supply to conduit 12. In this manner, the roots of the grassare watered directly by water that seeps through the permeable material,without evaporation loss. It is anticipated that the disclosed inventionwill result in a fifty percent reduction in water usage, due to reducedevaporation, for large grass areas such as playing fields and golfcourses. Moreover, because the system is fully contained below theground level, with no “pop-up” sprinker heads, there are no trippinghazards associated with the present invention. Additionally, due theopen cavity defined between the top and bottom permeable membranes, thesystem of the present invention has reduced resistance to fluid flowwhen compared with subterranean irrigation systems of the prior art.

[0017]FIG. 2A is a cross sectional view of one embodiment of thesheet-to-conduit connection means of FIG. 1 taken along line 2-2.Conduit 12 is shown having a slit 24 along one side, wherein eachmembrane of sheet 16 includes a recessed slot area that is friction fitalong the corresponding edge of slit 24. Accordingly, water 26 flowsfrom conduit 12, through slit 24 and into the central cavity area ofpermeable soaker sheet 16. Soaker sheet 16 may be secured to slit 24 byany number of means, including adhesive, heat welding, mating tabs andslots, clamping, and the like. Moreover, conduit 12 may be manufacturedintegral with sheet 16 so that the conduit and the sheet andmanufactured as a single unit, requiring no additional securement meansthere between.

[0018] Still referring to FIG. 2A, soaker sheet 16 comprises a top layeror membrane 16 a, a bottom layer or membrane 16 b and a space or cavity16 c positioned there between. Top and bottom layers 16 a and 16 b,respectively, typically are manufactured of a semi-permeable materialhaving a pore size large enough to pass fluid such as water at a rateequal to that needed to support vigorous lawn growth. The semi-permeableor permeable material may comprise a polysulfone such as a polyethersulfone, a cellulose material such as cellulose triacetate or cellulosetriacitate, a polyolefin, a polyetholene, or any material that willfunction to distribute fluid there through. In particular, the permeablemembranes preferably will have an average pore size in a range of 10nanometers to 10,000 nanometers, and a sheet thickness of two mils toten mils or more. Of course, the pore size and sheet thickness utilizedwill depend on the type of membrane material used and the fluid flowrate that is desired to pass through the membrane. Typically,hydrophilic membranes pass fluid more easily and, threfore, a smallerpore size would be used. Hydrophobic membranes typically pass fluidfluid less easily and, therefore, a larger pore size would be used. Ingeneral, planar soaker sheet 16 typically will have a thickness at leastten times smaller than the length and width dimensions of the sheet.However, any pore size or sheet thickness may be used as is desired fora particular application.

[0019] Central cavity 16 c offers minimal resistance to fluid flow sothat sheet 16 can be manufactured and installed in large sheets, forexample, sections measuring twenty feet by twenty feet, or more. Space16 c is maintained, i.e., not collapsed, by the water pressure of waterflowing there through, and by channel system 22 which is created by theplurality of holes 20 positioned along the sheet. In other words, eachof holes 20 is manufactured by sealing sheet 16 a and sheet 16 btogether around each hole 20, which provides a somewhat rigid gridshaped structure, thereby ensuring that space 16 c is maintained betweensheets 16 a and 16 b along channels 22.

[0020]FIG. 2B is a side cross sectional view taken along line 2B-2B ofFIG. 1 showing fluid channels 22, holes 20 and the upper and lowermembranes 1 6a and 16b, respectively, secured together. In this figure,turf roots 17 can be seen growing through apertures 20 of the planarsoaking sheet.

[0021]FIG. 3 shows a top view of a soaker sheet system 10 sized to fit aspecific shaped lawn area. In particular, conduit 12 is connected viapiping 28 to a water source (not shown). Conduit 12 is also connected toadditional conduits 30 via standard tee or cross-shaped fittings 32. Thefittings are capped with caps 33 at their ends along the edge of thesoaker sheet system. In the system shown, there are six soaker sheetsconnected to the water source, wherein each of the sheets includes ahole pattern 21 (only a small section of hole pattern 21 is shown forease of illustration) across the surface of each soaker sheet.Additionally, a particular sheet 34 also comprises a large hole 36 thatis heat welded around its edge 38 so that a tree or shrub may bepositioned within hole 36. If the shrub is very large so that it willnot fit through hole 36 upon installation, a cut or slice 40 may be madethrough sheet 16, wherein the slice is heat welded along its edges. Cut40 typically is aligned perpendicular to conduit 30 so that fluid flowin direction 42 from the conduit through the sheet is not hindered.Upper and lower membranes 16 a and 16 b typically are heat sealedtogether along the edge of cut 40, similar to the sealing treatmentaround holes 20 and shrub hole 36. In this manner, subterraneanirrigation system 10 can be custom fit around existing trees and shrubs.

[0022] By placement of this soaker sheet system beneath a sod lawn, theroot system of the lawn is directly irrigated from water delivered viathe subterranean system, without evaporation loss and without unsightlyand dangerous pop-up sprinkler heads. Moreover, any type of liquid maybe delivered to the plant roots by the subterranean irrigation system,thereby avoiding air exposure of dangerous chemicals such as weedkillers, insecticides, large doses of fertilizers, and the like.Subterranean application of such chemicals reduces the evaporation ofthe chemicals and reduces the risk of wind borne chemicals being carriedto adjacent locations. Accordingly, the subterranean irrigation systemof the present invention is safer for the environment and for humansthat use the planted area above and near the installed irrigationsystem.

[0023]FIG. 4 shows a cross sectional, isometric view of anotherembodiment of the soaker sheet and conduit of the present invention. Inthis embodiment, conduit 12 is secured to top and bottom soaker sheets16a and 16b, respectively, by adhesive 50. However, other securementmeans may be utilized such as heat welding methods. Rather thanincluding a slit along the conduit, which may structurally weaken thepiping, in this embodiment conduit 12 includes a plurality of holes 52positioned along a length of the conduit. Holes 52 allow water to freelyflow from an interior 54 of the conduit into cavity 16 c between top andbottom sheets 16 a and 16 b. This embodiment is preferred over the slittype embodiment shown in FIG. 1 due to the structural stability ofconduit 12, as will be understood by those skilled in the art. In thispreferred embodiment, conduit 12 may comprise a three-quarter inch outerdiameter header pipe such that the header pipe is easily connected tothe standard plumbing fittings of a water source supply line.

[0024] Holes 52 in conduit 12, also called perforations or apertures,typically extend along the header pipe from a location approximately sixinches from each end of the pipe. As shown in FIG. 1, the soaker sheetedge positioned adjacent the end of header pipe 12 typically is slightlyrecessed inwardly from the end of the pipe, such that adjacent soakersheets can be positioned in direct contact with one another along theiredges 18, while allowing for connection of adjacent conduits at threads14. In this manner, any number of mats can be connected together to forma relatively continuous system to cover any sized turf area. Moreover,multiple water sources may be provided throughout the system so thatwater pressure is maintained throughout the system. In other words, awater supply source outlet may be provided to every one thousand squarefoot area.

[0025] Spacing of holes 52 several inches from the end of each conduitensures that the holes allow the flow of water into space 16 c betweenthe upper and lower membranes 16 a and 16 b while not allowing the flowof water directly from the conduit into the ground. Accordingly, due tothe recessed region 56 of the soaker sheet adjacent end 58 of conduit12, shown in FIG. 1, the length 60 (a partial length is shown) of theheader pipe typically is the same as the width 62 (a partial width isshown) of the soaker sheet, also called an irrigation mat, attachedthereto. For example, in one embodiment, the irrigation system comprisesan individual conduit having a length 60 of eight feet, an irrigationmat having a width 62 of eight feet measured along the conduit, and alength 64 (a partial length is shown) of twenty feet measuredperpendicularly from the conduit. These large dimensions of the mat arefeasible due to the relatively unrestricted fluid flow cavity areaformed between the upper and lower membranes of the soaker mat.

[0026]FIG. 5 shows a top view of a subterranean irrigation system 10including several patches therein and wherein the system has beentrimmed to fit a particular sized turf area. The irrigation mat may betrimmed to fit irregular sized turf areas by simply cutting off theexcess mat area from a rectangular mat, such as in region 65, and heatsealing or other wise securing the top membrane of the lower membranetogether along edge of region 65. In one embodiment, the upper and lowermembranes are simply folded over one another to stop the flow of fluidthrough the hole created by removing the excess mat area.

[0027] Still referring to FIG. 5, repair kits can be provided wherein apatch 66 may be bonded to the upper or the lower membrane to patch ahole therein. The hole 68 may have been caused by initially cutting alarge hole in the mat for the placement of a post or a shrub thatsubsequently was removed. The hole requiring a patch may also havedeveloped as the result of damage to the mat. Another type of patch 70may comprise a small mat that is heat welded around three sides and isconnected to a small header pipe 72, wherein header pipe 72 is connectedto a fitting 74 on the initially installed system. The hole 76 overwhich patch 70 is placed typically is heat sealed around its edge priorto placing patch 70 over the hole. Locating such damaged areas of system10 can be accomplished by injecting a brightly colored liquid or foamingdye into the system.

[0028] In the preferred embodiment, conduits 30 are manufactured ofnon-metallic material such as PVC piping, wherein fittings 32 may bemanufactured of metal or may have a metal tab secured thereto, so that ametal detector can be used to located the installed, subterraneanfittings.

[0029] In the above description numerous details have been set forth inorder to provide a more through understanding of the present invention.It will be obvious, however, to one skilled in the art that the presentinvention may be practiced using other equivalent designs.

I claim:
 1. A subterranean irrigation system comprising: a conduitadapted for being secured to a fluid source and including a fluid flowaperture positioned therein; a first permeable membrane secured to saidconduit and defining an exposed top, planar surface of said irrigationsystem; and a second permeable membrane secured directly to said firstpermeable membrane and to said conduit and defining an exposed bottom,planar surface of said irrigation system, wherein said first and secondpermeable membranes define an enclosed, hollow cavity therebetweenwherein said fluid flow aperture communicates with said enclosed, hollowcavity.
 2. The irrigation system of claim 1 wherein said first permeablemembrane includes a plurality of apertures extending there through,wherein said second permeable membrane includes a plurality of aperturesextending there through and being positioned aligned with correspondingones of said plurality of apertures of said first permeable membrane,and wherein said second permeable membrane is secured to said firstpermeable membrane around each of said plurality of apertures of saidfirst permeable membrane so that said irrigation system defines apattern of apertures extending there through.
 3. The irrigation systemof claim 1 wherein said fluid flow aperture comprises a slit extendingsubstantially along a length of said conduit.
 4. The irrigation systemof claim 1 wherein said fluid flow aperture comprises a plurality ofapertures extending substantially along a length of said conduit.
 5. Theirrigation system of claim 1 wherein said first and second permeablemembranes are each manufactured of a material chosen from the groupconsisting of a polysulfone, a cellulose material, a polyolefin, and apolyetholene.
 6. The irrigation system of claim 1 wherein said first andsecond permeable membranes define a first sheet, and wherein said systemcomprises a plurality of sheets operatively connected to said conduit.7. The irrigation system of claim 1 wherein said pattern of aperturescomprises a waffle type pattern.
 8. The irrigation system of claim 1wherein said conduit comprises a rigid cylindrical member.
 9. Theirrigation system of claim 1 wherein said conduit is manufactured of amaterial chosen from the group consisting of metal, polyvinyl chloride,and plastic.
 10. The irrigation system of claim 2 wherein said enclosed,hollow cavity defines multiple channels of fluid flow extending aroundsaid pattern of apertures.
 11. A subterranean, planar irrigation systemcomprising: a fluid header adapted for being secured to a fluid sourceand including a fluid outlet positioned therein; a first permeablemembrane secured to said header and defining an exposed first, planarsurface of said irrigation system; and a second membrane secureddirectly to said first permeable membrane and to said header anddefining an exposed second, planar surface of said irrigation system,wherein said first permeable membrane includes a plurality of aperturesextending there through, wherein said second membrane includes aplurality of apertures extending there through and being positionedaligned with corresponding ones of said plurality of apertures of saidfirst permeable membrane, and wherein said second membrane is secured tosaid first permeable membrane around each of said plurality of aperturesof said first permeable membrane so that said irrigation system definesa pattern of apertures extending there through.
 12. The irrigationsystem of claim 11 wherein said first and second membranes define anopen space there between and wherein said fluid outlet communicates withsaid open space.
 13. The irrigation system of claim 11 wherein saidfirst and second membranes define a soaker sheet, and wherein saidsoaker sheet includes an enlarged aperture extending there through andbeing adapted for placement around a shrub.
 14. The irrigation system ofclaim 11 wherein said second membrane is secured to said first permeablemembrane by heat welding along at least a portion of an edge of saidsecond membrane.
 15. The irrigation system of claim 11 wherein saidfirst permeable membrane includes pores therein, wherein said pores havean average diameter size in a range of 10 nm to 10,000 nm and whereinsaid first permeable membrane has a width, a length and a thickness, andwherein said thickness is less than ten times smaller than said widthand said length.
 16. The irrigation system of claim 11 wherein saidfirst and second membranes define a soaker sheet, and wherein saidsoaker sheet is trimmed along an edge to have a predetermined shape. 17.The irrigation system of claim 11 wherein said system comprises aplurality of first permeable membranes secured to corresponding ones ofa plurality of second membranes, and wherein said system furthercomprises a patch positioned on at least one of said first membranes.18. The irrigation system of claim 11 wherein said patch is connecteddirectly to said fluid header.
 19. A method of irrigating a lawn area,comprising the steps of: providing an irrigation device including afirst permeable planar membrane and a second permeable planar membranewherein said first and second membranes are secured together to define ahollow cavity there between; placing said irrigation device on a groundsurface; covering said irrigation device with a living plant groundcover; providing a fluid flow to said hollow cavity such that the fluidflow passes through said first and second permeable membranes to contactsaid ground surface and said living plant ground cover.
 20. The methodof claim 19 wherein said irrigation device comprises a plurality ofholes extending there through, said holes adapted to allow unhinderedroot growth through said irrigation device.
 21. The method of claim 19wherein said living plant ground cover comprises dirt and grass seedtherein.
 22. The irrigation system of claim 11 wherein said secondmembrane is secured to said first permeable membrane by adhesive alongat least a portion of an edge of said second membrane.